This invention relates to improved methods and apparatus for biofeedback and display of respiration performance. In particular, it relates to systems for optimizing air delivery to the lung. Spontaneous breathing, as well as augmented breathing utilizing respiratory assistive devices, may be improved. In addition, this concept includes systems for inhalation therapy treatment for efficient delivery of aerosol and/or dust particles to the lung with optimum individualized breathing patterns.
Breathing patterns are defined by the size of the breath (tidal volume), the number of breaths per minute (respiratory frequency), the time ratio of inspiration to expiration (inspiration/expiration ratio), and the volume/time (flow) waveform patterns within the above noted volume and time constraints. The desirable breathing pattern to combat certain types of health problems may be quite different from the patterns necessary for mechanically assisted breathing, for aerosol/dust delivery to the lungs or for other clinical problems. For example, in problems of diseases generally classified as airway obstructive -- such as e.g. asthma, bronchitis or emphysema -- there is a need for a slow respiratory rate, long expiratory time ratio, and a relatively large tidal volume and breathing waveform patterns that may be quite unique to the individual. By contrast, the patient with so-called restrictive lung disease, e.g. pulmonary fibrosis, or many other diseases that may cause a loss of lung volume without airway obstructive problems of dominant significance, efficient breathing generally requires smaller tidal volumes, a more rapid respiratory rate, and a more rapid expiratory time ratio, again with breathing wave forms that might be guite unique. Regardless of underlying lung disease, when the patient receives assistive breathing with or without the added requirement for aerosol/dust delivery to the lungs, other sets of optimized breathing patterns may be needed for the particular patient, above and beyond the pattern requirement for normal spontaneous breathing. In any of the above noted problems, the expiratory phase is desirably "passive", that is, passive recoil of the elastic lung/chest wall structures force the air out of the patient with maximum ease and efficiency, minimum patient engergy expenditure, and minimum increases in lung pressure to thereby avoid so-called "dynamic bronchial compression" and further restriction to the airflow passages. However, in many airway obstructive problems, particularly those due to advanced emphysema with an excessively prolonged expiration time, a variable portion of the terminal expiratory phase should be variably "active", that is, utilizing active muscular contracture to force that air out of the lungs.
The normal respiration rate for humans is about 12 to 15 cycles per minute, with an inspiration:expiration time ratio of about 1:1.4. A typical 70 Kg adult human has a tidal volume of about 500 cc. A lifetime of experience combined with instinctive breathing patterns tend to provide respiration having characteristics that are ingrained in the persons individual physiology. When a person encounters an abnormal breathing situation with different mehanical contraints for efficient breathing, it may require extensive training to modify his established habits and instinctive rhythms.
Adapting to an abnormal respiratory condition frequently requires the subject to adopt a slower respiratory rate, for instance, a rate reduction from rapid gasping breathing of perhaps 25 cycles/minute to normal respiratory rates, or sometimes even less than 12 cycles/minute, particularly for diseased lungs with an "airway obstructive" disease. The expiration time is often longer, resulting in a lower inspiration: expiration ratio, e.g.--1:2 to 1:3.
In order to maintain adequate oxygen supply and carbon dioxide elimination, the tidal volume is increased to compensate for the slower cycle rate. These patterns may require particularly extensive training. In addition to training for ordinary quiet breathing, where the person is at rest, it is often desired to train for an exertion pattern to permit increased active physical activity. Special problems in respiratory control are encountered in suppressing a "panic attack", which may result from a patient's coughing spasm or excitement, which results in rapid gasping breathing which will interfere with pulmonary functions.
Widespread emphysema is a major health problem, and this invention is intended for use in training and treatment of persons suffering from this disorder. Emphysema can particularly cause dynamic bronchial compression, which calls for specially prescribed respiration.
For chronic emphysema patients learning a prescribed respiration cycle, it is mandatory to achieve the volume of air necessary to sustain life. In such cases, the training permits the patient to learn an overall breathing cycle which consumes minimum energy and reduces the distress of shortness of breath.
Shortness of breath, dyspnea, may thereby be treated in diseased patients with a variety of disorders. Dyspneic patients having difficult or labored respiration may be trained to respond to effective patterns.
Teaching a normal person dynamic breath control, with musical voice or instrument breathing control or improving respiratory functions for underwater diving, mountaineering or various atheletic activities, can also employ breathing training systems.
It should be apparent from the above, that breathing patterns must be highly individualized for the particular problem. Considering that desirable breathing patterns may be very different from the pathologic breathing patterns, and that the prescribed breathing patterns may be difficult for a patient to learn, it should also be apparent that there is a need to quantitate and document suboptimal performance, particularly for research-oriented purposes and thereby quality control, as well as performance documentation for the above noted special purposes in the normal subject.
Biological feedback training (biofeedback training) refers to the art of sensing usually unrecognized body physiologic functions with suitable transducers, and displaying these functions by suitable means in order that the patient may be made aware immediately of body function performance. Through this technique, the patient interacts with a displayed signal to optimize the body function. Many patients can become aware of otherwise unobserved body function, and often learn to influence favorably these functions in a relatively rapid training period. Of particular effectiveness and value is so-called "primary reinforcement", (herein described as "positive" biofeedback) wherein a basic body function is used as part of the stimulus to biofeedback training. Dyspnea relief with efficient breathing patterns would be a type of primary reinforcement biofeedback training.